Method of cold shaping partitioned tubular steel articles



June 23, 1959 KAUL METHOD OF COLD SHAPING PARTITIONED TUBULAR STEELARTICLES 6 Sheets-Sheet 1 Filed April '7, 1954 INVENTOR. Ben Kira/Z wATTORNEYS 6 Sheets-Sheet 2 B. KAUL METHOD OF GOLD PING PARTITIONEDTUBULAR S L. ARTICLES SHA TEE June '23, 1959 Filed April 7, 1954INVENTOR.

Ben [(wuL f ATTORNEYS June 23, 1959 B. KAUL 2,891,298

. METHODOF cow SHAPING PARTITIONED TUBULAR STEEL. ARTICLES Filed April7, 1954 6 Sheets-Sheet 4 INVENTOR. Bezz Kwugl m KAUL SHAPING PARTITIONEDTUBULAR STEEL. ARTICLES B. METHOD OF COLD ATTORNEYS Filed April 7. 1954June 23, 1959 B. KAUL METHOD OF COLD June 23, 1959 SHAPING PARTITIONEDTUBULAR STEEL. ARTICLES 6 Sheets-Sheet 5 Filed April 7, 1954 I H l m 4we. I 2 F q B 3 i 9 9 l 8 l 7 9 w M l 1: FL 5 NH 1 II I! w: H.441 IL |I|"pl INVENTOR. Ben Kwu/L BY %w&

ATTORNEYS 2,891,298 ONED June 23, 1959 B. KAUL METHOD OF cow SHAPINGPARTITI TUBULAR STEEL ARTICLE Filed April 7. .1954

IN V EN TOR. Ben K'wwl EQQ ATTORZVEIGS United States Patent ()fiice2,891,298 Patented June 23, 1959 METHOD OF COLD SHAPING PARTITIONEDTUBULAR STEEL ARTICLES Ben Kaul, Warren, Ohio, assignor, by mesneassignments,

to American Radiator & Standard Sanitary Corporation, New York, N.Y., acorporation of Delaware Application April 7, 1954, Serial No. 421,561 13Claims. (Cl. 29-131) tubular walls extending in each direction from thepartition wall.

Partitioned. tubular steel articles have been made for and used for avariety of purposes, among others, as the body of a rocket shellincluding a motor tube extending in one direction from a partition walland a warhead tube extending in the other direction from a partitionwall located intermediate the ends of the rocket body or shell.Heretofore, such rocket bodies have been made of steel in a pluralityofpieces' or components welded or otherwise secured together, including,for instance, a motor tube component, a warhead tube component, apartition component, etc., each fabricated separately and thereafterjoined together to form the finished rocket.

Difficulties, however, have been encountered in the manufacture of sucha completed article from a plurality of components from the standpointof accuracy in concentn'city, alignment, wall thickness and uniformityof strength in the assembled components, as well as the soundness orefliciency of the joints, however formed, between the components, inpreventing leakage under pressure between the compartments formed oneither side of the intermediate partition wall.

I have discovered that the leakage difliculties or defects maybe avoidedby making the completed article integrally from a one piece startingblank. In this manner, the partition wall metal can be cold worked insuch manner as to develop the necessary strength, hardness and lack ofporosity to resist pressure orleakage to which it maybe subjected fromeither side thereof.

Likewise, concentricity in an axial direction of the two i i tubularportions extending in either direction from the intermediate partitionwall, uniformity in wall thickness of either of the tubular portions atany cross section,

the desired strength and hardness characteristics of the.

metal in the walls of the tubular and partition portions, and otherdesirable characteristics can be developed in the finished product byforming the same in one piece by cold working from a single startingblank of low carbon and preferably low manganese steel, Without heattreatment to develop the desired physical properties.

These results, however, can only be achieved by following a certain coldworking procedure in which con centricity is initiated throughout theblank and maintained during each forming operation, provided that thenecessary forming pressures are developed and sustained during each coldworking step without destroying a characteristic, shape, condition orform established or completed in one or more portions of the article bya previous operation. g 3 l The manufacture of a partitioned tubularsteel article .tricity is always maintained.

from low carbon steel by cold working and by satisfying the foregoingconditions or requirements presents a most diflicult problem where theprocessing is to be carried out Without metal loss incident to the coldworking, shaping, flowing, or forming operations required to provide thedesired finished shape with strong, sound, leakproof andpressure-resistant walls having the necessary concentricity. The problemis even more complex where it is necessary to create and duplicate thesame properties, conditions and shapes within extremely close tolerancesand limits in all completed articles intended to be the same.

, Thus with respect to the last mentioned consideration, where there isabsolute uniformity, piece by piece, in the manufacture of rocketshells, the motor and warhead portions thereof may be charged withuniform amounts of propellants and explosives and the performancethereof more accurately predicated without selecting and grading,because it will be known that each piece is identical with every otherpiece as to weight, Wall thickness, concentricity, etc.

I have discovered a solution to this complex problem involving aprocedure or series of steps in the cold working of a steel blank and inwhich the series of steps are interrelated and coordinated such thatpartitioned tubular articles of the type described may be successfullyproduced by cold shaping operations including cold extrusion steps toobtain a desired finished shape, concentricity, uniformity, strength andhardness provided by the cold working, with a substantial reduction inthe cost of making such articles as compared with the manufacture ofcomparable but less accurate articles from a plurality of separatelyformed pieces or components later joined togeth'er. s

Fundamentally, the new procedure involves so controlling the character,location and direction of metal flow in the blank as the same issubjected to cold working under compression in successive stages, thatthe desired wall thickness, strength and shape may be provided in thetubular portions extending in either direction from the intermediatepartition wall; that the directed flow of metal, and the zones of metalcold worked, in any stage of the procedure, does not interfere with thedirected flow and cold working of metal in the same or different zonesof the blank in subsequent stages of the procedure; and that thedirected metal flow and zone of metal coldworked in a zone of the metalextending in one direction from the intended location of the partitionwall are related during any working operation to the metal in the otherzone of the blank extending in the other direction from the intendedlocation of the partition Wall such that concen- Accordingly, it is ageneral object of the present invention to provide a new method of coldshaping a tubular steel article to provide a finished article havingconcentric tubular walls extending in each direction from anintermediate partition wall.

Furthermore, it is an object of the present invention toprovide a newprocedure of cold working a tubular steel article having concentrictubular walls extending in either direction from an intermediatepartition wall in which the partition wall metal is strong, dense andpressure-resistant.

Also, it is an object of the present invention to provide a new methodof making a partitioned tubular steel article by cold working, from astarting blank or slug of low carbon steel without metal loss incidentto the forming or cold working of the article.

Finally, it is an object of the present invention to solve the complexproblems stated, to eliminate difficulties in the manufacture ofpartitioned tubular steel articles, to generally improve cold workingprocedures, and to ob tain the foregoing advantages and desiderata in aneffective and simple manner.

These and other objects and advantages, apparent to those skilled in theart from the following description and claims, may be obtained, thestated results achieved, and the described difliculties overcome by themethods, steps, operations,'procedures and discoveries, which comprisethe present invention, the nature of which are set forth in thefollowing general statements, a preferred embodiinent ofwhich-illustrative of the best mode in which applicant has contemplatedapplying the principles-is set forth in the following description andshown in the drawings, and which are particularly and distinctly pointedout and set forth in the appended claims forming part hereof.

The nature of certain discoveries and improvements in my method of coldshaping partitioned tubular stee articles may be stated in general termsas preferably including the steps of drawing a tubular wall through adie opening and against a punch in one direction during forward movementof the punch and in then expanding the metal in the tubular wall uponretracting the punch therefrom.

The nature of other discoveries and improvements in my method of coldshaping partitioned tubular steel articles may be stated in generalterms as including the steps of forming a blank by compression with areduced diameter at one end and an expanded diameter at the other end,then completing the tubular wall formation in the expanded diameter endof the blank, then expanding the reduced diameter end of the blank, andthen forming a tubular wall in the initially reduced and subsequentlyexpanded diameter end of the blank.

By way of example, the improved method of the present invention is shownsomewhat daigrammatically in the accompanying drawings forming parthereof, wherein:

Figure l is a perspective view of a metal blank cut from a piece of barsteel as received from the mill which is used as a starting blank in thecold shaping method of th present invention;

Fig. 2 is a somewhat diagrammatic sectional view illustrating the firstor slug sizing operation of the new cold shaping method;

Fig. 3 is a view similar to Fig. 2 showing a first backward extrusionoperation at the motor end of the blank in the new cold shaping method;

Fig. 4 is a View similar to Fig. 3 showing the next, for- Ward extrusionoperation of the motor end of the blank;

'5 is a View similar to Fig. 4 showing the next drawing operationperformed on the motor end of the blank;

Fig. 6 is a view similar to Fig. illustrating the next compressing andexpanding operation performed on the head end of the blank;

Fig. 7 is a view similar to Fig. 6 showing the next back- -w ardextrusion operation performed on the head end of the blank;

Fig. 8 is a View similar to Fig. 7 showing the second backward extrudingand partition working operation performed on the head end of the blank;

Fig. 9 is a view similar to Fig. 8 showing the next forward extrusionoperation performed on the head end of the blank;

Fig. 10 is a view similar to Fig. 9 showing the next operation performedto expand the bourreleet at the head end of the blank and optionally tofurther work the metal in the partition wall;

- Fig; 11 is a sectional view of the blank illustrated in Fig. 1 used as'a starting blank for the operation shown in ,Fig. 2;

Fig. 12 is a sectional view of the blank produced by the operation shownin Fig. 2 and which constitutes the starting blank for theoperationshown in Fig. .3;

Fig. 13 is a View similar to Fig. 12 illustrating the blank produced bythe operation shown in Fig. 3 which constitutes the starting blank forthe operation shown in Fig. 4; r

Fig. 14 is a view similar to Fig. 13 illustrating the blank produced bythe operation shown in Fig. 4 which constitutes the starting blank forthe operation shown in Fig. 5;

Fig. 15 is a view similar to Fig. 14 illustrating the blank produced bythe operation shown in Fig. 5 which constitutes the starting blank forthe operation shown in Fig. 6.;

Fig. 16 is a view similar to Fig. 15 illustrating the blank produced bythe operation shown in Fig. 6 which constitutes the starting blank forthe operation shown in Fig. 7;

Fig. 17 is a view similar to Fig. 16 illustrating the blank produced bythe operation shown in Fig. 7 which constitutes the starting blank forthe operation shown 1n Fig. 8,

Fig. 18 is a view similar'to Fig. 17 illustrating the blank produced bythe operation shown in Fig. 8 which constitutes the starting blank forthe operation shown in Fig. 9;

Fig. 19 is a view similar to Fig. 18 illustrating the blank produced bythe operation shown in Fig. 9 which constitutes the starting blank forthe operation shown in Fig 10;

Fig. 20 is a view similar to Fig. 19 illustrating the blank produced bythe operation shown in Fig. 10;

Fig. 21 is a sectional view of a completed product made by the methodillustrated; and

Figs. 22, 23, 24 and 25 are views similar to Figs. 5 and 15 illustratinga modification of the draw-through pro- 'cedure.

Similar numerals refer to similar parts throughout the various figuresof the drawings. a

In the drawings, the improved method illustrates the manufacture of aone piece, partitioned, tubular steel article which may be a rocketshell; but the invention is not limited to the manufacture of a rocketshell, or the particular partitioned article illustrated, inasmuch asthe discoveries of the invention may be used for the manufacture ofpartitioned tubular steel articles intended for other purposes and ofdifferent sizes, wall thicknesses, etc.

The starting blank for the new method is indicated at 1 in the drawingsand is illustrated as a cylindrical slug which may be cut from bar stockas rolled and as received from the steel mill. Preferably, if thephysical properties required in the finished article involve say 100,000lb. per sq. in. strength and a relatively high Rock- .well B scalehardness, the steel should be low carbon and low manganese steel, suchas (3-1012 steel. Although the use of a cylindrical slug is preferredwhere a cylindrical tubular article is to be produced, nevertheless, thesolid starting blank or slug 1 may have a different cross sectionalshape such as oval, square, rectangular, hexagonal, etc., depending onthe .character of the finished article to be produced.

The amount .of steel present in the blank 1 is determined by the amount.of steel to be present in the finished article since there is no scraploss 'in'carrying out the new cold shaping steps of the improved method.

.Thus, the blank 1. will have the proper weight and size for forming thedesired finished article; and the steel used need not be a special orpremium analysis steel but as indicated may be an ordinary low carbonsteel.

.Bar steel as received from the steel mill may be slightly out of roundor have slight diameter variations and these variations must beeliminated from the starting blank in order to preclude die injury orthe formation That is to ,say, if true circular cross sections are to beobtained and true concentrici-ty between the inner and outer wallsurfaces of the tubular portions of the finished article :is

:tobe maintained, and uniformity from piece to piece is also to bemaintained; the actual slug or blank used must be processed to provide atruly concentric blank.

Accordingly, the first step in the procedure is in part a slug sizingoperation for providing a truly concentric blank and eliminating otherdimensional variations which may be present in the bar stock from whichthe starting blank is cut.

The slug should not be smaller in diameter than the diameter of thefinishedarticle for otherwise extra operations may be involved inconnection with providing sufiicient metal in the proper places in theblank to carry out the necessary forming operations, to at the same timecomplete the article to proper size or diameter, and to enable the blankto be made truly round.

The diameter of the starting blank 1 is such that one end; portionthereof may be expandedlaterally to provide atruly circular shape incross section for subsequent forming operations, and that the otherportion may be compressed laterally to form it with a truly circularcross section while still of a diameter substantially that of thefinished product.

Preferably, the starting blank 1 is pickled, provided with a bonderizingcoating, and then coated with soap or other usual drawing compoundcoating. The blank 1 isthen placed in the slug sizing die, generallyindicated at 2 (Fig. 2), the blank 1 being shown in dot-dash lines inFig. 2 at the start of the operation. Die 2 is formed with a cavity 3which has an upper cylindrical portion 4 provided with a rounded uppercorner 5 and connected by an angular shoulder 6 with a reducedcylindrical portion 7 which may be slightly tapered for draft. The dieportion 7 terminates in a cylindrical knockout opening 8.

A punch generally indicated at 9 is associated with the die 2 having amain cylindrical shank 10 and a rounded corner 11 merging with a furthercylindrical shank portion 12 having a close sliding fit withincylindrical die cavity portion 4 so that the punch is centered andguided in its movement within the die cavity 3. The punch portion 12terminates in a nose formed by ,a rounded corner 13 merging into a flatbottom or end Wall 14; and a knockout member 15 is associated with theknockout opening 8 of the die. After blank 1 is inserted in die 2, punch9 is moved downward and engages the top of the blank, the location onthe punch at this time being shown by dot-dash lines in Fig. 2.Continued downward movement of the punch applies a compressive forcedriving the blank downward in die cavity 3. The punch nose formed byrounded corner 13 and flat nose end wall 14 enters the metal in the topof the blank and forms a central fiat bottomed recess 16 in the top ofthe resulting sized slug generally indicated at 17 in Figs. 2 and 12. a

As the punch moves downward the compressive force exerted flatwise onthe top of the metal in the blank by theflat punch nose acting on top ofthe blank causes the blank metal to flow and fill out and expand in theupper portion of the blank into the die cavity portion panding the outerperiphery of the 4 above the die cavity shoulder 6. The compressiveforce exerted by punch 9 in forming recess 16 in exupper portion of theblank to increase the diameter thereof may be accompanied by a verysmall amount of backward extrusion around the punch nose. At the sametime, the compressive force exerted by punch 9 pushes the lower end ofblank 1 .into the smaller diameter cavity portion 7 to reduce thediameter of this portion of the blank and .form it under compressionwith a truly circular cross under compression at removes all out ofroundness ent in the bar stock from which the blank 1 was cut.

section.

The cold working of the blank 1 to form the prepared blank 17 thusaccurately sizes the periphery of the blank all sections to be trulyround and that may have been pres- 1 blank 17 (Fig;"12 thus formed bythe slug sizing operation illustrated in Fig. 2 has an upper ex pandedportion 18 of larger diameter thanthe diameter of the slug 1 and a lowerreduced diameter portion 19 of smaller diameter than the diameter ofslug 1 with an angular shoulder 20 connecting the expanded and reduceddiameter portions 18 and 19. The portion 19 also has a diametersubstantially that of the finished article or that portion thereofformed from the' lower end of the blank 17.

In forming the sized or prepared blank 17, the metal in the upperportion of the blank below the recess 16 is cold worked somewhat, andthe metal in the outer annular portions of the expanded portion 18 andreduced portion 19 is cold worked somewhat, accompanied by some workhardening. However, the metal in the remainder of the blank is only coldworked to a slight extent and is not appreciably work hardened so thatit may be subjected to substantial cold working in the next operationwithout any annealing.

The angular shoulder 20 on the prepared blank 17 is so located andformed with respect to the blank portions 18 and 19 at either end of theshoulder thata subsequent backward extrusion may be performed on theexpanded portion 18 of the blank in one operation and without annealing,and which backward extrusion may form a deep hole in theexpanded portion18' of the blank with an exterior shoulder intervening the ends of thebackwardly extruded blank that may be used for subsequently forwardlyextruding the backwardly extruded metal to provide an elongated thintubular wall at one end of the blank having the desired finisheddiameter and which finished diameter approximates the diameter of thereduced diameter portion 19 of the starting blank 17.

After the slug sizing operation has been completed in the dieillustrated in Fig. 2, punch 9 may be withdrawn and the sized slug 17ejected from the die by knockout member 15, sufficient clearance beingprovided as illustrated in Fig. 2 between the top of the knockout member15 and the final location of the sized slug 17 in die 2 to prevent anybottoming of the sized slug on the knockout member during theoperationillustrated.

The sized slug 17 may then be washed, pickled, and bonderized in theusual manner and provided with a usual draw compound coating inpreparation for the next operation illustrated in Fig. 3, wherein theblank 17 is shown in dot-dash lines at the start of the operation. Theoperation illustrated in Fig. 3 is essentially a backward extrusionoperation and is performed in a die generally indicated at 21 having acavity provided with an upper cylindrical portion 22 and a rounded uppercorner 23. The cylindrical portion .22 is connected by an angularshoulder 24 with a reduced cylindrical portion 25 which in turn isconnected by an angular shoulder 26 with a further reduced portion 27having the shape of the reduced portion 19 of prepared blank 17. Thelower end of the die cavity terminates in a knockout opening 28 in whicha knockout support member 29 is located.

A punch generally indicated at 30 is associated with die 21 having amain cylindrical shank portion 31 provided with a rounded corner 32 andthe shank 31 has a close sliding fit within cylindrical die portion 22so that the punch is centered and guided in its movement therein. Therounded corners 23 and 32 insure proper entry and alignment of punch 3t?in die 21 when performing the backward extrusion operation on preparedblank 17 inserted in die 21. The punch shank 31 is joined by a fillet 33with a cylindrical nose 34 terminating in a tapered end portion 35joined by a rounded corner 36 with a tapered nose portion 37 terminatingin a flat central nose portion 38. l After the blank 17 is inserted indie 21, as shown in dot-dash lines in Fig. 3, punch 30 is moved downwardand engages the top of .blank 17, the location of the punch at this timealso being shown by dot=dash lines. Continued downward movement of punch30 within the die cavity applies a compressive force first from the flatnose end portion 38 and then from the entire nose portion of the punchwithin recess 16 of blank 17, which recess 16 centers the blank withrespectto the punch nose.

During continued downward movement of the punch 30 in die 21, the metalin the upper portion 18 of blank 17 is displaced first outwardly andthen outwardly up w-ard, backward of the direction of punch travel, toradially fill the cylindrical portion 25 of the die cavity. During thisdownward movement of the punch the axial length of the upper portion ofthe blank is increased because of the backward extrusion, and at thesame time, the metal in the lower portion of the blank is pusheddownward somewhat in the die cavity portion 27 to fill out the diecavityportion above member 29 and to bottom on the top of the support member29 which may be shaped with the fiat portion 39 terminating in anannular angular portion 40 somewhat similar in shape to the portions 14and 13 respectively of punch 9.

An extruded blank 41 is thus formed which may be ejected from the diecavity by support member 29 upon withdrawal of punch 30. The extrudedblank 41 (Fig. 13) has a cup formation 42 at the upper or motor endthereof extending above an angular shoulder 43 which terminates below inthe reduced diameter portion 44 having a fiat shallow recess 45 in itsbottom end, similar to the recess 16 formed in the upper end of startingblank 17.

There are a number of important aspects to the particular. manner inwhich the backward extrusion operation of the motor end of the blank iscarried out as illustrated in Fig. 3 to produce the backwardly extrudedblank 41 shown in Fig. 13. First of all, the diameter of punch noseportion 34 should be equal to or larger than the finished insidediameter of the motor tube to be formed at the motor end of the blank.Second, in order to eliminate excessive pressures, the metal in theblank is allowed to move outward and upward freely as illustrated inFig. 3 within die cavity portion 25 which is larger in diameter than theouter diameter of the upper end portion 18 of the prepared blank asshown in dotdash'lines in Fig. 3.

Third, because of the free outward expanding of the metal in a wallportion 42 of the resulting blank 41, any hidden seams that may havebeen present in the bar stock from which the starting slug 1 has beenformed will be opened up, enlarged and made clearly visible for removal.The enlarging of the seams or other imperfections on the outer surfacesof the upper portion 42 of blank 41 due to the expansion thereof enablesgrinding operations to be performed readily on the blank 41 whereby theseams may be removed and will not result in defects in the finishedpart.

Fourth, the downward pressure of punch 30 is resisted by the bottomingof the blank metal on support member 29 so that the metal in the upperregion of the blank must flow upwardly and outwardly freely around thepunch nose as the punch descends; and at the same time, a centeringdepression for a punch in a subse- .quent operation is formed at 45 onthe lower end of the blank.

Because of the substantial cold working to which the blank 41 has beensubjected, it is substantially wlork hardened and must be annealed toprepare it for subsequent operations. The annealing operation may becarried out, following the removal of seams, by washing, and by heatingthe blank 41 to from 1250 F. to 1450 F, followed by pickling,bonderizing and the application of another drawing compound coating. Theblank 41 is now ready for the next or forward extrusion operation shownin Fig. 4 which may be performed in a die generally indicated at 46formed with a cavity 8 having an upper cylindrical portion 47 with arounded upper corner 48, an extrusion shoulder 49, a reduced cylindricalextrusion orifice portion 50 and relieved guide opening 51. v

A punch generally indicated at 52 is associated with the die 46 having amain cylindrical shank 53 formed with an extrusion shoulder 54 whichmerges into a re duced nose portion 55. The punch portion 53 has a closesliding fit within cylindrical portion 47 of the die cavity so that thepunch is centered and guided in its movement within the die cavity, therounded corner 48 cooperating with the extrusion shoulder 54 to insureproper entry and alignment of the punch 52 in the die 46.

When the blank 41 is inserted in die 46, as shown in dot-dash lines inFig. 4, the shoulder 43 thereof rests on the die extrusion shoulder 49with the blank portion 44 extending downward through extrusion orifice50. After blank 41 is inserted in die 46, punch 52 is moved downward andits nose enters the blank until the punch extrusion shoulder 54 engagesthe top annular surface of upper side wall portion 42 of blank 41. Thelocation of the punch at this time also is shown by dotdash lines inFig. 4.

Continued downward movement of punch 52 applies an extrusion pressure orforce through extrusion shoulder 54 to the upper end of the side walls42 of blank 41 and the metal in the thick side walls is forced undercompression downward and is extruded through the escape area betweenextrusion shoulder and orifice 50 and punch nose 55. This forwardextrusion operation not only thins and elongates the metal in the sidewalls of the piece at the motor end of the blank but work hardens thesame to the desired degree of hardness depending upon the character ofthe restricted escape or flow area between the punch and extrusionshoulder through which the metal is extruded.

The final limit of downward movement of punch 52 and of the extrudedtubular blank 56 resulting from the forward extruding operation areshown in full lines in Fig. 4, the blank 56 also being illustrated inFig. 14. A flange 57 remains at the upper end of the tubular side walls58 at the motor end of blank 56, and side walls 58 extend upward fromthe head end of the blank 59 which has the same shape as the portion 44formed in the blank 41 by the operation shown in Fig. 3. The blank 56 isthen washed, pickled, bonderized and providcd with a drawing compoundcoating in-preparation for the next draw through operation illustratedin Fig 5.

The draw through operation is performed in a usual manner with a usualdie and punch illustrated respectively at 60 and 61 in Fig. 5, the blank56 being placed in die 64) initially as shown in dot-dash lines in Fig.5, and the punch 61. then being moved downward to draw the blank throughthe die 69 to form the drawn blank 62 illustrated in Fig. 15 and in fulllines in Fig. 5.

The draw through operation of Fig. 5 reduces the thickness of the sidewalls of the motor end of the tube, indicated at 63 to the desiredcompleted cylindrical size, the metal in the side walls 63 being workedto final hardness and to develop the desired physical characteristicstherein. The metal in the head end 5? of the blank not having been coldworked following the annealing operation performed on the blank 41,remains soft so that it may be subjected to further cold workingoperations. The draw through blank 62 is now ready, without furtherpreparation, to be subjected to further operations to provide thedesired formations on the head end of the blank.

Before describing the further operations carried out on the blank 62,several aspects of the procedure carried out in the forward extrusionoperation of Fig. 4 and the draw-through operation of Fig. 5 warrantcomment. The blank 56 (Fig. 14) produced bythe forward extrusionoperation of Fig. 4 shows a slight enlargement or bulge indicated at 64,at the" region where the side wa1ls'58 join the head end 59 of the blank56, the bulge 64 also being indicated in Fig. 4 in full lines and inFig. 5 in dot-dash lines. 1

This bulge 64 occurs during the forward extrusion operation of Fig. 4and is apparent by measuring actual blanks 56 produced by the operation.When blank 41 is placed in die 46 and punch 52 descends, the punchforces some of the metal in shoulder 43 of blank 41 under compressionagainst the die orifice 5 in such manner as to produce an outwardresultant when the pressure or compression is relieved, as when aportion of the metal in what was once the shoulder portion 43 of blank41 passes to the relieved die portion 51. Because of the relativelylarge volume of metal in the particular region of shoulder 43, the metalin passing through orifice 50 is not stressed to anywhere near itselastic limit; 'and after passing into the clearance zone 51 (Fig. 4)the metal tends to expand slightly as indicated at 64. While thislocalized expansion 64 is reduced in diameter momentarily when theknock-out member associated with die 46 (not shown) ejects the blank 56from die 46 since the metal in the expanded portion 64 was not stressedbeyond its elastic limit, the expanded portion 64 springs back, orrecovers, after ejection of blank 56, so that the localized expandedportion 64 is present in the completed blank 56, as shown in Fig. 14.

While this metal flow or shaping is taking place, the metal in the headend 59 of blank 56 is neither subjected to pressure nor worked, and theshape of portion 59 remains unchanged. However, since the metal in theblank 56 forming the extruded tubular side Walls 58 is stressed beyondits elastic limit during the extrusion operation, it retains incompleted blank 56, the inner and outer diameters resulting from thediameters of the die orifice opening 50 and of the punch nose 55. Whenthe blank 56 is then subjected to the drawthrough operation of Fig. 5,the bulged or expanded portion 64 is eliminated or ironed out in drawingblank 56 through the die 60 to form the blank 62.

Referring to Figs. 22, 23, 24 and 25, a slightly modified form of punch61a is illustrated for carrying out the draw-through operation of Fig.5. Fig. 22 represents the punch 61a and draw-through die 60 and drawnblank 62a in substantially the same relative positions as correspondingelements in Fig. excepting that the blank 62a has completed its limit ofdownward movement in the draw-through operation past the stripping ring65. The punch 61a is provided with an annular recessed groove .66 havinga lower outwardly downwardly angled annular corner 67 into which themetal in the upper .end 57 of blank 56 flows during the draw-throughoperation to produce a thickened upper end portion 68 at the upper endof the side walls 63 of the drawn through blank 62a. This thickenedblank upper end side wall portion 68 is illustrated in-Fig. 23, whichrepresents a cross-section of the blank at the stage of the draw throughoperation illustrated in Fig. 22, assuming that the blank 62a could beremoved from punch 61a at this time without shape change, which, ofcourse, is impossible. The thickened blank portion 68 has a lowerangular annular shoulder 69 formed by the punch recess shoulder 67.Referring to Fig. 24, when the draw-through punch 61:; is retracted tostrip the punch from the blank 62a, the punch recess shoulder 67 expandsthe thickened blank portion 68, held by the stripping ring 65, so that:the thickened portion 68 is enlarged as indicated at 70 -in Fig. 25providing an outturned flange portion at the :upper end of drawn throughblank 62a.

In other words, the punch 61a is undercut at 66 and 67 so as to form thethickened portion 68 on the downstroke of the draw-through operation;and in retracting the punch 61a, the undercut shoulder 67 expands thealso being shown by dot-dash lines.

the head end portion 59 stantially the same, as indicated by acomparison of the full and dot-dash lines in Fig. 6, defining the upperend 'portion of the blank 62 before and after forming. There upper endof the blank to enlarge the thickened pontion 68 and form an outturnedthickened flange 70. In this manner, the drawn through blank 62 of Fig.15 may be provided with a thickened outturned flange portion at theupper end of its side walls 63 as illustrated in the blank 62a of Fig.25.

The blank 62 or 62a now may be subjected to further operations forforming the head end of the final product from the metal in the head end59 of blank 62 or 62a, the motor end side walls 63 of the article havingbeen completed or finished.

The next operation, that is the compressing and expanding of the headend 59 of the blank 62 or 62a, may be performed in a die generallyindicated at 71 in Fig. 6. The die 71 is formed with a cavity having anupper cylindrical portion 72, a shoulder 73, a reduced cylindricalportion 74, another shoulder 75, a further reduced cylindrical portion76 and a flared end 77 communicating with an enlarged portion 78 at itslower end. The upper cylindrical portion 72 is provided at its upper endwith a rounded corner 79, as shown.

A punch generally indicated at 80 is associated with the die 71 having amain cylindrical shank 81 provided with a rounded corner 82, and theshank 81 has a close sliding fit within cylindrical die portion 72 sothat the punch is centered and guided in its movement therein. Therounded corners 79 and 82 insure proper entry and alignment of punch 80in die 71 when performing the backward extrusion operation on blank 62or 62:: inserted in die 71. The punch shank 81 is joined by a fillet 83with a cylindrical nose 84 terminating in a fiat end 85 joined byrounded corner 86 with cylindrical nose portion 84.

Also associated with die 71 is a support member generally indicated at87 having a cylindrical portion 88 centered and closely fitting withincylindrical die portion 78. Support member 87 mounts a tubular supportshank 89 having side walls slightly concave in cross-section asindicated at 90, terminating in an annular upper end portion 91 having ashape complementary to the shape of the surface 92 at the bottom of therecess formed by the tubular walls 63 of blank 62. A knockout pin 93extends 'throughsupport members 87 and 89 and is provided with anenlarged knockout member 94 with a head 94a slidably mounted within theenlarged recess 95 at the upper end of support shank 89.

The blank 62 of Fig. 15 is turned upside down or endfor-end from theposition illustrated in Fig. 15, and inserted in die 71, as shown indot-dash lines in Fig. 6. The punch 80 is then moved downward andengages the top of blank 62, the location of punch 80 at this time Theblank 62 as thus inserted and positioned within the die 71 is centeredwithin the die by being supported on support shank 89,

as shown, which support shank 89 and support member 87 are centered inthe die cavity as previously described. Meanwhile, punch 80 is centeredwithin die 71 and the nose 84 thereof is centered with respect to blank62 in the initial engagement with the blank by the recessed formation 45in the end of the head 59 of the blank. This recess 45 was formed in theoperation illustrated in Fig. 3

'and the formation 45 is not disturbed or changed in either of theoperations illustrated in Figs. 4 and 5, as indicated at 45 in theblanks illustrated in Figs. 14 and 15.

Continued downward movement of punch 80 within the die cavity 71 appliesa compressive force from the Hat end 85 of the punch within recess 45'of blank 62. During such movement the metal in the head end 59 of theblank is displaced first outwardly to radially fill the cylindricalportion 74 of the die cavity. During this downward movement of thepunch, the axial length of of the blank 62 remains sub- 11 may be a veryslight increase in the axial length of the head end portion 59, toosmall to indicate in the drawings, incident to a slight amount ofbackward extrusion which may occur during the head expanding operation.

A blank 96 is thus formed which may be ejected from the die cavity byknock-out pin 93 upon withdrawal of punch 80. The blank 96 (Fig. 16) hasan enlarged head end 97 7 formed from the metal in head end 59 of blank62 (Fig. 15), the head end 97 joining the tubular motor end wall 63 byan anular shoulder 98, and terminating upwardly in a thick annular wallportion 99 extending upward from a thick partition wall portion 100.

There are a number of important aspects of the compressing and expandingoperation performed on the head end of the blank carried out asillustrated in Fig. 6 to produce the blank 96 shown in Fig. 16, and ofthe particular shaping of the expanded head end 97 of the blank 96. Whenthe ultimate hole or cavity to be formed in the head end of the blankmust have the same internal diameter as, or a larger diameter than, theinternal diameter of the finished tubular walls 63 of the motor end ofthe blank, it becomes necessary to provide for a resistance area in somemanner on the motor end of the blank to supplement the resistance area101 at the motor end surface of partition wall 100, so that the totalmotor end resistance area is greater than the pressure which must beapplied to the head end of the blank to displace and flow the metaltherein for later forming the head end of the blank to cylindrical shapewith a hole or cavity.

In the operation illustrated in Fig. 6 a punch is used with a nose 84slightly smaller in diameter than the internal diameter of thecylindrical walls 63 to expand and compress the metal in the head end 59of blank 62 to the expanded shape 97 in blank 96. In so doing, thesupport area of support member portion 91 and knock-out member head 94ais slightly greater than the area of punch nose 34 so that as punch nose34 moves downward into head end portion 59 of blank 62, the head endportion 59 is supported at 101 and the metal therein expands outwardlyaround and is compressed under fiat end 85 of punch nose 84.

As a result of expanding the head end 59 of the blank 62 to form theexpanded head end portion 97 of blank 96, the shoulder 98 is formedwhich now provides a resistance area which, added to the area of thebottom 101 of recess in the motor end of the blank, is as great orgreater than the area at the bottom end of the ultimate hole to beformed in the head end of the blank. In this manner the shape of theblank has now been prepared to enable a tubular hole to be formed in thehead end of the blank as large as or larger than the internal diameterof the finished tubular wall 63.

The metal in the head end 59 of blank 62 is soft prior to the operationillustrated in Fig. 6 but the metal in the walls 63 thereof is hard, thedesired hardness having been developed therein by cold working. Incarrying out the operation illustrated in Fig. 6, to compress and expandthe head end to the shape indicated at 97 in Fig. 16, the metal in thehead end 97 does not become as hard as the metal in the walls 63 of themotor end of blank 96. However, because the mass of metal in head end97, partially hardened, exceeds the strength of the thin finishedwork-hardened tubular walls 63,-it is necessary in order to further coldwork the metal in the expanded end 97 of blank 96, to locally anneal thesame. Such local annealing of the metal in the head end 97 of blank 96is also necessary to prevent fracture during the next operation of thezone of metal between the hard and partially hardened expanded metal.

This local annealing operation of the enlarged portion 97 of blank 96may be carried out in a usual manner, preferably by induction heatingthe portion 97 of blank 96 while maintaining the motor end walls 63 coldby water sprays so as to prevent the annealing heat from effecting thehardness previously developed in the tubular I2 walls 63. The annealingoperation may be carried out by the localized heating of head endportion 97 to about 1450? F. followed by washing, pickling, bonderizing,and the application of another drawing compound coating.

The blank 96 is now ready for the next backward extrusion operationshown in Fig. 7 which may be performed in a die generally indicated at102 formed with a cavity having an upper cylindrical portion 103 with arounded upper corner 104, a shoulder 105, a reduced cylindrical portion106, another shoulder .107, and a reduced cylindrical portion 108communicating with an enlarged portion 109 at its lower end.

A punch generally indicated at 110 is associated with the die 102 havinga main cylindrical shank 111 provided with a rounded corner 112, and theshank 111 has a close sliding fit within cylindrical die portion 103 sothat the punch is centered and guided in its movement therein. Therounded corners 104 and 112 insure proper entry and alignment of punch110 in die 102 when performing the backward extrusion operation on blank96 inserted in die 102. The punch shank 111 is joined by a fillet 113with a cylindrical nose 114 terminating in a flat end 115 joined by arounded corner 116 with cylindrical nose portion 114.

Also associated with die 102 is a support member generally indicated at117 having a cylindrical portion 118 centered and closely fitting withincylindrical die portion 109. Support member 117 mounts a tubular supportshank 119 having side walls slightly concave in crosssection asindicated at 120, terminating in an upper end portion 121 having a shapecomplementary to the shape of the surface 101 of blank 96. A knock-outpin 122 extends through support members 117 and 119 and is provided withan enlarged knock-out member 123 with a head 124 slidably mounted withinthe enlarged recess 125 at the upper end of support shank 119.

Blank 96 is inserted in die 102, as shown in dot-dash lines in Fig. 7,and the shoulder 98 rests on die shoulder 107 with initially a slightclearance 126 between blank surface 101 and the top end of supportmember 121 and knock-out head 124, as shown in Fig. 7. After blank 96 isinserted in die 102, punch 110 is moved downward within blank walls 99until it engages the top of thick partition wall 100, also as shown indot-dash lines in Fig. 7. The blank 96 as thus inserted in die 102 andsupported on support member 117 is centered with respect to the die andthe punch 110; the punch and support members being centered with respectto the die cavity as previously described, and the cavities in the blank96 being con centric as previously described.

Continued downward movement of punch 110 applies an extrusion pressureflatwise from the flat end 115 of the punch against the metal in thethick partition wall 100 of the blank 96 to drive the blank downward andseat blank surface 101 on the upper end of support member 121 andknock-out member head 124 and to rearwardly extrude metal in the blankoutwardly and then outwardly upward, backward of the direction of punchtravel, within die cavity portion 106, the upper portion of which may beslightly relieved for clearance at 106a to provide a slightly largerdiameter as shown at 106b. During this downward movement of the punch110 the axial length of the head end portion 97 of blank 96 is increasedbecause of the backward extrusion, and at the same time, the metal inpartition wall 100 is substantially reduced in thickness.

A blank generally indicated at 127 is thus formed which may be ejectedfrom the die cavity by knock-out pin 12 2 upon withdrawal of punch 110.The blank 127 (Fig. 17) has a head end portion 128 joining the tubularmotor end wall 63 by an annular shoulder 129, and terminating upwardlyin elongated thick annular wall portion 130 extending upward frompartition wall portion .131, the partition wall portion being providedwith an upper head end recess surface 132 and a lower motor end recesssurface 133.

In carrying out the operation illustrated in Fig. 7, the outer diameterof the head end portion 128 may be slightly enlarged over the outerdiameter of the head end portion 97 of blank 96, and the internaldiameter of thick walls 130 may be formed slightly larger than theinternal diameter of thick wall portion 99 of blank 96 as the hole 134is deepened therein.

Furthermore, the hole 134 in blank 127 is slightly larger in diameterthan the ultimate hole to be formed in the head end; and preferably thebottom surface 132 of the hole, that is the top surface of partitionwall 131, is shaped with a tapered angular portion 135 for purposes tobe later described. The blank 127 has now been prepared so as to enablethe final formation of the center section or partition Wall of theultimate product; which preparation includes the described enlargeddiameter of hole 134, the enlarged outer diameter of wall portion 130,and the particular formation of the hole bottom surface 132-135.

The metal in the head end portion 128 of blank 127 has again becomehardened by cold working in performing the operation shown in Fig. 17and must again be locally annealed in the manner previously describedwith respect to the blank 96, followed by washing, pickling,bonderizing, and the application of another drawing compound coating.During the annealing operation, the finished wall 63 is maintained coldby water sprays to prevent affecting the physical properties previouslydeveloped therein by coldworking.

In forming the blank 127, the area of shoulder 98 of blank 96 and thesupport area 101 provides sufficient resistance area or strength toresist the pressure of punch nose 114 entering the head end of the blankfor carrying out the backward extrusion operation.

The blank 127 is now ready for the next backward extruding and partitionwall coining operation shown in Fig. 8 which may be performed in a diegenerally indicated at 136 formed with a cavity having an uppercylindrical portion 137 with a rounded upper corner 138, a shoulder 139,a clearance portion 140 slightly reduced at shoulder 141 and connectedwith cylindrical portion 142 terminating in a shoulder 143 and a reducedcylindrical portion 144 communicating with an enlarged portion 145 atits lower end.

A punch generally indicated at 146 is associated with die 136 having amain cylindrical shank 147 provided with a rounded corner 148, and theshank 147 has a close sliding fit Within cylindrical die portion 137 sothat the punch is centered and guided in its movement therein. Therounded corners 138 and 148 insure proper entry and alignment of punch146 in die 136 when performing the operation on blank 127 inserted indie 136. The punch shank 147 is joined by a fillet 149 with acylindrical nose 150 terminating in a rounded nose end 151 having aslightly conical central nose end surface 152.

Also associated with die 136 is a support member generally indicated at153 having a cylindrical portion .154 centered and closely fittingwithin cylindrical die portion 145. Support member .153 mounts a tubularsupport shank 155 having side walls slightly concave in cross- "sectionas indicated at 156, terminating in an upper end portion 157 having ashape desired for shaping the bottom end of the recess in the motor endof the blank. A knock-out pin 158 extends through support members 153and 155 and is provided with an enlarged knock-out memher 159 with ahead 160 slidably mounted within the enlarged recess 161 at the upperend of support shank the metal therein to theshape shownin Fig. 8. Inthis operation, the outer diameter of the thickened head end ducedwithin die cavity portion 142 so that the metal in and adjacent thepartition wall is compressed both axially and radially to form a soundpartition wall metal struc In thus cold working and flowing metal in thepartition wall, a certain amount of backward extrusion takes place whichelongates the side walls of the enlarged head end portion of the blankas shown by comparing the dotdash and full line showing of the upperends of the blanks in Fig. 8. These operations, including the reducingof the outside diameter of the head end of the blank adjacent thepartition wall, the coining of the metal in the partition wall, and theaxial and radial compression of the metal in the partition Wallconstitute the final stage in what may be termed a grain crossing stepin the cold'working of the metal in the partition wall. 1 A blank 162 isthus formed which may be ejected from the die cavity by knock-out pin158 upon withdrawal of punch 146. The blank 162 (Fig. 18) has a furtherelongated expanded head end 163 joining the tubular motor end wall 63 byan annular shoulder 164, and terminating upwardly in a thick annularwall portion 165 extending upward from the substantially finishedpartition wall portion 166. p

In performing the operation illustrated in Fig. 8, no substantial coldworking of the metal in wall portion 165 is performed so that this wallportion is not workhardened but remains soft. The only work-hardenedportion is the metal in the zone of the partition wall 166 in which thedesired physical properties have now been developed as well as in thepreviously work-hardened motor end tubular Wall 63. j 1

In shaping the blank 162, sufiicient metal remains at rounded areas 167which are formed from the zones in the blank 127, at the upper surfaceof partition wall 166 from which the bourrelet may subsequently beexpanded. The metal in annular zone 167 was not work hardened undercompression because it was not contacted by the rounded portion 151 ofpunch 146, as shown in full lines inFig. 8. If the work-hardening of themetal in partition wall 166 has resulted in any substantialwork-hardening of the metal at an immediately adjacent shoulder 164 inblank 162, then this portion of the blank only should be locallyannealed in the manner previously described while maintainingthepartition wall 166 and motor end wall 63 cool by water sprays toprevent the physical properties developed therein from being affected.

The local annealing is then followed by pickling, bonderizing, and theapplication of another drawing compound coating; and the blank 162 isnow ready for the next or forward extrusion operation shown in Fig. 9which may be performed in a die generally indicated at 168 formed with acavity having an upper cylindrical portion 169 with a rounded uppercorner 170, an extrusion shoulder 171, and a reduced cylindricalextrusion orifice 172 terminating in a guide opening 173.

A punch generally indicated at 174 is associated with die 168 having amain cylindrical shank 175 formed with an extrusion shoulder 176 whichmerges into a reduced nose portion 177. The punch portion 175 has aclose sliding fit within cylindrical portion 169 of the die cavity sothat the punch is centered and guided in its movement within the diecavity, the rounded corner 170 cooperating with the extrusion shoulder176 to insure proper entry and alignment of the punch 174 in the die168.

When the blank 162 is inserted in die 168, as shown in dot-dash lines inFig. 9, the shoulder 164 thereof rests on the die extrusion shoulder 171with the blank portion 63 extending downward through the extrusionorifice 172. After blank 162 is inserted in die 168, punch 174 is moveddownward and its nose enters the blank until the. punch extrusionshoulder 176 engages the top annular surface of side wall portion ofblank 162 Continued downward movement of punch 174 applies an extrusionpressure or force through extrusion shoulder 176 to the upper end of theside walls 165 of blank 162 and the metal in the thick side walls 165 isforced under compression downward and is extruded through the es cape.area between extrusion shoulder 171 and orifice 172, and punch nose 177.This forward extrusion operation not only thins and elongates the metalin the side walls of the head end 163 of the blank 162 but workhardensthe same to the desired degrees of hardness, depending upon thecharacter of the restricted escape or flow area between the punch andthe die extrusion shoulder through which the metal is extruded.

The final limit of downward movement of punch 174 and of the extrudedtubular blank 178 resulting from the forward extruding operation areshown in full lines in Fig. 9, the blank 178 also being illustrated inFig. 19. A, flange 179 remains at the upper end of the tubular sidewalls 180 at the head end of the blank 178, said side walls, 180extending upward from the motor end of the blank 178 and from theintermediate partition wall 166, the motor end side walls again beingindicated at 63.

The blank 178 now has thin work-hardened tubular side walls 63 and 180having the same external diameter, this diameter being smaller than thediameter of the thickened wall portion 163 of blank 162 and beingsmaller than the initial diameter of the starting slug 1. Below theflange 179, the side walls 180 may be slightly thicker as indicated at181 for a purpose to be subsequently described, this thickened portion181 being formed in die 168 by the enlarged die recess 182 belowextrusion shoulder 171 and above escape orifice 172.

The blank 178 is then washed, pickled, bonderized and provided with adrawing compound coating in prepara tion for the next operation ofexpanding the bourrelet, illustrated in Fig. 10.

The operation of expanding the bourrelet is performed in a diearrangement generally indicated at 183 including a cylindrical diecavity 184 in a die block supported on a support block having anenlarged opening 185 receiving a lower support member generallyindicated at 186 having a cylindrical portion 187 centered and guided indie portion 185. The lower support member 186 is formed with a reducedcylindrical portion 188 above portion 187, a hollowed portion 189, andan enlarged head 190 provided with a fiat central projection 191.

Above the upper end of die 183 is a blank centering fixture 192, andassociated with die 183 is a punch generally indicated at 193 having acylindrical portion 194 and a tapered nose portion 195 terminating in aslightly convex nose end 196.

As shown in Fig. 10, the lower support member portions 188 and 1198contact within the motor end side walls 63 of blank 178 supportedthereon, and center the same with respect to die 183, the support member186 being centered with respect to the die cavity as explained.

Relief portion 189 of lower support member 186 does not internallycontact the side walls 63 of blank 1'78. Fixture 192 engages the outsideof the head end side walls 188 of blank 178 and centers the same withrespect to the die cavity. Punch cylindrical portion 194, as shown, isof smaller diameter than the internal diameter of blank walls 188.

After the blank 178 is inserted in die 183, punch 193 is moved downwardand the nose portions 195 and 1% thereof engage the head end surface ofpartition wall 166, the motor end partition wall surface being supportedon .top of lower support member 186. Continued downward movement ofpunch 193 applies expanding and compressive forces to the partition wallmetal. Tapered nose portion 195 engages the rounded area 167 previouslyformed in blank 162, which formation 167 remained in blank 178, andpunch portion 195 drives metal from the upper portion of rounded areas167' slightly outward to expand stopped by the cylindrical opening 184of the die 183.,

This expanded bourrelet is small, but ofa usual nature and tapers intothe motor and head end side walls 63 and 188, being generally indicatedin the drawings by the numeral 197 in the resulting blank generallyindicated at 198 in Fig. 20. As the metal in the rounded areas 167 canno longer move outward on continued downward movement of punch 193 indie 183, the rounded punch nose portion 196 drives the metal toward thecenter of the partition wall or axis of blank 198, resulting in a slightcentral thickening of the partition wall as. indicated at 199 in Fig.20, the underside of the partition wall 199 being formed with a slightcentral recess 280 by the sup-.

port member formation 191.

This thickening and inward movement ofthe metal in the partition wall199 of blank 198 also completes the grain crossing step in the coldworking of the metal in the partition wall.

The blank is then removed from die 183, and as illustrated in Fig. 20,the blank 198 with the expanded bourrelet 197 and finished petition wall199 has finished head end side wall portions 188 and motor end side wallportions 63 in which all physical properties required have beendeveloped by the various cold working operations except in flange 179and thickened portion 181 at the upper end of the head end, the shape ofwhich has not been completed.

The upper end of blank 198 may then be subjected to a usualstress-relieving operation in the zone of the flange 1'79 and thickenedportion 181, and then washed, pickled and bonderized and subjected to ausual series of drawing and nosing operations with intervening stress.relief etc. until the desired head end shape 201 is developed as shownin Fig. 21. The metal originating in flange 179 and thickened wallportion 181 in blank 198 provides metal for substantial metal thicknessat the nosed-in end of the blank after the nosing operations have beencompleted and thus provides sufficient metal for internally threadingthe head end as indicated at. 202 in the final article illustratedgenerally at 283 in Fig. 21.

The article 283 may then he threaded internally as at 294 at the end ofmotor end walls 63. The motor end walls 63 and head end walls 201 thusextend from the strong partition wall 199 integrally in one piece, thearticle 2113 having been formed from a single metal blank by coldworking operations.

Articles cold formed in the manner described have been tested underhydrostatic pressures without failure or leakage in either directionthrough the partition Wall, indicating the sound, dense, sealed andleakproof metal structure in the partition wall as well as in the headand motor end walls extending integrally therefrom.

One of the fundamental aspects of the present invention is themaintenance of true concentricity throughout in every operation whichresults in the final product 203 having true concentricity throughoutwith uniform wall thicknesses at any cross-section. Thus a productresults which has a partition wall intermediate its endsandsubstantially uniform diameter throughout its length from the openend of the motor end to the zone in the head end where the nose tapersinward, except for the slight intended enlarged diameter where thebourrelet was expanded.

Furthermore, due to the strength and metal structure of the partitionwall, it may be subjected to extreme pressures from either side thereofwithout failure, thus providing a rocket body which need not be made ina plurality of pieces or components, and which does not have lack ofuniformity as to concentricity, alignment, wall thickness and uniformlyof strength which lack of unibly of a plurality of components.

Another fundamental aspect of the present invention is the relationshipbetween the series of operations performed in obtaining the double-endedgenerally cylindrical product with tubular side walls of substantiallythe same diameter extending in either direction from the partition wall.This result is obtained by starting with a blank 1 of preselecteddiameter, somewhat greater than the diameter of the finished article;compressing one end portion of the blank to havea reducedcross-sectional area, which may, for example, be the head end of theblank; carrying out the necessary operations on the other or enlargedend of the blank to form the tubular side walls of the motor end of theblank; then expanding the reduced cross-sectional area head end of theblank to a larger diameter than the initial diameter of the startingblank; and carrying out the series of operations thereon to form thetubular walls of the head end of the blank.

In this manner, suflicient support areas are formed in the blank forholding the blank in the several succeeding operations so that fullycold worked or completed wall portions of the blank are not ruptured orfractured or broken away from other portions of the blank being workedin any operation; and so that the support areas thus developed, directand control the nature, location and direction of metal flow in theparticular operation being carried out.

Finally, another aspect of the invention is the ability to providewhatever formation is desired in the tubular walls of the partitionedtubular steel article. For instance, the outturned thickened flangedportion 70 at the motor end of the blank may be formed, as illustratedin Fig. 25.

Accordingly, the present invention provides a new procedure for themanufacture of partitioned tubular steel articles by cold shapingintwhich manufacturing costs are reduced, scrap losses are eliminated,and difiiculties avoided which heretofore have been encountered in themanufacture of such partitioned articles from a plurality of components;in which uniformity of the partitioned product manufactured ismaintained as to concentricity, alignment wall thickness and strength;and which accomplishes the many new functions hereinafter described, andovercomes prior art difficulties and solves long standing problems inthe art.

In the foregoing description, certain terms have been used for brevity,clearness and understanding; but no unnecessarylimitations are to beimplied therefrom beyond the requirements of the prior art, because suchterms are utilized for descriptive purposes herein and not for thepurpose of limitation and are intended to be 1 principles, elements,combinations, and subcombinations,

and mechanical equivalents obvious to those skilled in theart are setforth in the appended claims.

1. The method of cold working a one-piece steel blank to form apartitioned tubular article having a partition wall and concentrictubular walls extending in each directionfromthe partition wall, thesteps of axially comfpressingJa blank and, forming a reduced diameter atone end and an expanded diameter at the other end thereof; then coldworking the metal in the expanded diameter end of the blank to form afirst tubular wall; then axially tcompressing and radially expanding thereduced diameter end of the blank; and then forming a second tubularwall in the initially reduced and subsequently expanded diameter end ofthe blank.

2. The method of cold working a one-piece steel blank to form apartitioned tubular article having a partition wall and concentrictubular walls extending in each direction from the partition wall, thesteps of axially compressing a bar-like steel blank of nominal diameterand by said axial compression expanding the nominal diameter at one endand reducing the nominal diameter at the other end of said blank toconcentrically size the same; then cold extruding a first concentrictubular wall in the expanded diameter end of the blank and developingdesired physical characteristic in said first wall by said cold working;then axially compressing the reduced diameter end of the thus-formedblank and expanding the diameter thereof to be greater than the externaldiameter of said first tubular wall; then cold extruding a secondconcentric tubular wall inl the greater expanded diameter end of theblank and developing desired physical characteristic in said secondwalltby said cold working; leaving a partition wall intermediate saidfirst and second tubular walls; and cold working the metal in saidpartition wall to develop a sound grain structure and desired physicalcharacteristics therein.

3. The method of cold working a one-piece steel blank to form apartitioned tubular article having a partition wall and concentrictubular walls extending in each direction from the partition wall withthe tubular walls of substantially the same diameter at least adjacentthe partition wall; the steps of axially compressing a barlike steelblank of nominal diameter larger than the external diameter of thearticle to be made, and by said axial compression, expanding the nominaldiameter at one end of said blank, reducing the nominal diarneterlat theother end of said blank toa diameter substantially that of the articleto be made, and concentrically sizing the expanded and reduced diameterblank; then cold backward and forward extruding a first concentrictubular wall with a diameter vsubstantially the same as the reduceddiameter end of the blank in the expanded diameter end of the blank;then axially compressing the reduced diameteruend of the thus-formedblank and expanding the diameterthereof to be greater than the externaldiameter of said first tubular wall; then cold backward and forwardextruding a secondt concentric tubular wall in thegreater expandeddiameter end vof the blank to, a diameter substantially the same as thediameter of the first tubular wall; leaving a partition wallintermediate said first and second tubular walls; and cold working themetal in said partition wall to develop a sound grain structure therein,

4. The method of cold working a one-piece steel blank to form apartitioned tubular steel article having a partition wall and concentrictubular walls extending in each direction from the, partition wall, thesteps of axially compressing a barn-like steel blank of nominal diameterand by said axial compression expanding the nominal diameter at one endand reducing the nominal diameter at theother end of said blank toconcentrically size the same; then cold backward extruding and furtherenlarging the diameter of the expanded diameter end of the blank to forma thick tubular wall in the expanded diameter end of the blank and toform a hole therein of a diameter at least as large as the finishedinside diameter of a first tubular wall to be subsequently formed fromsaid backwardly extruded thick tubular wall; then cold forward extrudinga first concentric tubular wall having an external diameterapproximating the diameter of the reduced diameter end of the blank fromthe metal in said backwardly extruded thick tubular wall; then axiallycompressing the reduced diameter end of the thus-formed blank andexpanding the diameter thereof to be greater than the external diameterof said first tubular wall; then cold extruding a second concentrictubular wall in the greater expanded diameter end of the blank; leavinga partition Wall intermediate said first and second tubular walls; andcold Working the metal in said partition wall to develop a sound grainstructure therein.

7 5. The method of cold working a one-piece steel blank to form apartitioned tubular steel article having a partition wall and concentrictubular walls extending in each direction from the partition wall; thesteps of axially compressing a bar-like steel blank of nominal diameterand by said axial compression expanding the nominal diameter at one endand reducing the nominal diameter at tile other end of said blank toconcentrically size the same, and at the same time by said axialcompression forming a first concentric recess in the expandeddiameterend of the blank; then cold backward extruding by axialcompression an enlarged tubular wall in the expanded diameter end of theblank, centering the application of said axial compression by said firstconcentricrecess, and by said backward extruding pressure "forming asecond concentric recess in the reduced diameter end of the blank; thencold forward extruding a first concentric tubular wall from the metal inthe backward extruded wall; then axially compressing the reduceddiameter end of the thus-formed blank and expanding the diameter thereofto be greater than the external diameter of said first tubular wall, andcentering the application of said axial compression to said reduceddiameter and by said second recess previously formed therein; then coldextruding a second concentric tubular wall in the greaterexpandeddiameter end .of the blank; leaving a partition wallintermediate said first and second tubular walls; and cold Working themetal in said partition wall to develop a sound grain structure therein.

6. In a method of cold working a tubular steel blank,

the steps of forming a cup-shaped blank, forwardly extruding anelongated tubular wall with an outturned extrusion flangeat its free endfrom the metal in the side walls of the cup-shaped blank, drawing thetubular Wall through a die opening and against a punch in one directionduring forward movement of the punch and forming a thickened inturnedflange-like wall portion from the metal in the extrusion flange at thefree end of the tubular wall during said forward punch movement, and

then expanding the metal in the inturned flange-like wall portion uponretracting the punch' from within the tubular wall to form an outwardlyprojecting thickened Wall portion at the free end of the tubular wall.

7. The method of cold working a one-piece steel blank to form apartitioned tubular steel article having a partition wall and concentrictubular walls extendingin each direction from the partition wall, thesteps of axially compressing a bar-like steel blank of nominal diameterand by said axial compression expanding the nominal diameter at one endand reducing the nominal diameter at the other end of said blank toconcentrically size the same; then cold extruding a first concentrictubular wall in the expanded diameter end of the blank; then axiallycompressing the reduced diameter end of the thus-formed blankandexpanding the diameter thereof to be greater than the external diameterof said first tubular wall, and by said axial compression forming a holein the greater expanded diameter end of the blank having a diametersmaller than the internal diameter of said first tubular Wall; then coldextruding a second concentric tubular Wall in the greater expandeddiameter end of the blank;

leaving a partition Wall intermediate said first and secondtubular-walls; and cold Working the metal in said partition wall todevelop a sound grain structure therein.

8. The method of cold working a one-piece steel blank to form apartitioned tubular steel article having a partition wall and concentrictubular walls -extending-in each direction from the partition wall, thesteps of axially rcompressing a bar-like steel blank of nominal diameterand by said axial vcompression expanding-the nominal diameter at one endand reducing the; nominal diameter;

at the other end of said blank to concentrically size the same; thencold extruding a first concentric tubular wall in the expanded diameterend of the blank; then axially compressing the reduced diameter end ofthe thus-formed blank and expanding the diameter thereof to be greaterthan the external diameter of said firsttubular wall, and by said axialcompression forming a hole separated from said first tubular wall by athick partition wall portion in the greater expanded diameter end of theblank having a diameter smaller than the internal diameter of said firsttubular wall, and by said axial compression also forming an externalshoulder joining the greater expanded diameter end of the blank with thefirst tubular wall; then supporting the thus-formed blank on saidshoulder and on said thick partition wall portion within the firsttubular wall; then cold extruding metal from said thick partition wallportion thereby increasing the diameter and depth of said hole and theexternal diameter of said greater expanded diameter end of thethus-supported blank, and reducing the thickness of said thick partitionwall portion; then cold working the metal in said partition wall todevelop a sound grain structure therein; and then cold extruding asecond concentric tubular wall in the greater expanded diameter end ofthe blank.

9. The method of cold working a one-piece steel blank to form apartitioned tubular steel article having a partition wall and concentrictubular walls extending in each direction from the partition wall, thesteps of axially compressing a bar-like steel blank of nominal diameterand by said axial compression expanding-the nominal diameter at one endand reducing the nominal diameter at the other end of said blank toconcentrically size the same; then cold extruding a first concentrictubular wall in the expanded diameter end of the'blank; then axiallycompressing the reduced diameter end of the thus-formed blank andexpanding the diameter thereof to be greater than the external diameterof said first tubular wall, and by said axial compression forming a holeseparated from said first tubular wall by a thick partition wall portionin the greater expanded diameter end of the blank having a diametersmaller than the internal diameter of said first tubular wall; thenfurther axially compressing the greater expanded diameter end of theblank toefurther enlarge the diameter thereof and to increase thediameter of said hole to be larger than the ultimate hole to be formedtherein and to form an annular tapered angular portion on a surface ofsaid thick-partition wall portion at the bottom of said hole; thenreducing the external and internal diameters of the metal in the greater.expanded diameter end of the blank surrounding the hole and compressioncold working the metal in said partition wall to develop a sound grainstructure therein; and then cold extruding a second concentric tubularwall in the greater expanded diameter end of the blank.

10. The method of cold working a one-piece steel blank to form apartitioned tubular steel article having a partition wall and concentrictubular walls extending in each direction from the partition wall, thesteps of axially compressing a bar-like steel blank of nominal diameterand by said axial compression expanding the nominal diameter at one endand reducing the nominal diameter at the other end of said blank toconcentrically size the same; then cold extruding a first concentrictubular wall in the expanded diameter endof the blank; then axiallycompressing the reduced diameter end of the thus-formed blank andexpanding the diameter thereof to be greater than the external diameterof said first tubular wall, and by said axial comv endofjth e blanksurrounding said hole; and then cold extruding a second concentrictubular wall in the greater expanded diameter end of the blank.

11. The method of cold working a one-piece steel blank to form apartitioned tubular steel article having a partition wall and concentrictubular walls extending in each direction from the partition wall, thesteps of axially compressing a bar-like steel blank of nominal diameterand by said axial compression expanding the nominal diameter at one endand reducing the nominal diameter at the other end of said blank toconcentrically size the same; then cold extruding a first concentrictubular steel wall in the expanded diameter end of the blank; thenaxially compressing the reduced diameter end of the thus-formed blankand expanding the diameter thereof to be greater than the externaldiameter of said first tubular wall, and by said axial compressionforming a hole separated from said tubular wall by a thick partitionwall portion in the greater expanded diameter end of the blank; thenaxially and radially compressing the metal in said thick partition wallportion and forming a rounded fillet-like area in the partition wallsurface at the bottom of said hole; then cold extruding a secondconcentric tubular wall in the greater expanded diameter end of theblank; and then radially expanding metal from said rounded area to forman expanded annular band surrounding the article adjacent said partitionwall and intervening the first and second concentric tubular walls.

12. The method of cold working a one-piece steel blank to form apartitioned tubular steel article having a partition wall and concentrictubular walls extending in each direction from the partition wall, thesteps of axially compressing a bar-like steel blank of nominal diameterand by said axial compression expanding the nominal diameter at one endand reducing the nominal diameter at the other end of said blank toconcentrically size the same; then cold extruding a first concentrictubular wall in the expanded diameter end of the blank; then axiallycompressing the reduced diameter end of the thus-formed blank andexpanding the diameter thereof to be greater than the external diameterof said first tubular wall, and by said axial compression forming a holeseparated from the first tubular wall by a thick partition wall portionin the greater expanded diameter end of the blank; then axially andradially compressing the metal in said thick partition wall portion andforming a rounded fillet-like area in the partition wall surface at thebottom of said hole; then cold extruding a second concentric tubularwall in the greater expanded diameter end of the blank; then expandingportions of the metal from said rounded area to form an annular expandedhand around the article adjacent said partition wall, and at the sametime axially compressing other metal in said rounded area and displacingthe same inward to thicken said partition wall portion.

13. In a method of shaping a metallic blank to form an article having aninterior partition wall intermediate a first tubular end portion and asecond tubular end portion, the steps of cold working said first endportion to size an inside diameter therein smaller than the insidediameter of said second end portion and the outside diameter thereofgreater than the outside diameter of said second end portion and by saidcold working causing metal contained in said partition wall to beexpanded radially outwardly; and then subsequently cold working saidfirst end portion to reduce the outside diameter thereof and by saidcold working causing metal contained in said partition wall to be:simultaneously compressed partially radially inwardly and partiallyradially outwardly, said cold Working being initiated by axially opposedcompressive forces; and said cold working further causing permanentdeformation of said metal contained in said partition wall.

References Cited in the file of this patent UNITED STATES PATENTS1,598,240 Carlson Aug. 31, 1926 2,079,102 Biginelli May 4, 19372,237,993 Korbuly Apr. 15, 1939 2,371,716 Snell Mar. 20, 1945 2,668,345Eckstein Feb. 9, 1954 2,748,465 Bodinaux June 5, 1956 2,772,470 LyonDec. 4, 1956 FOREIGN PATENTS 869,595 France Feb. 5, 1942 1,010,338France Mar. 19, 1952 OTHER REFERENCES Iron Age, Oct. 19, 1950, pp. and71.

